Actually my experience with 2 people travelling on the one PNR was the opposite in the sense that both of us were upgraded. One was Gold and one was Silver.

I would not split PNR's. If the load controller working the flight needs to move some folks from Y-J, and then J-F, he/she is more likely to pull 2 at once, rather than having to split the booking (ie move you, and leave your colleague where he is).

The proportion of Golds being op-upped from J-F is far less than people from Y-J, so set your expectations low. As far as we can all tell, op-ups happen according to status and then alphabetically (my last name starts with a C) but my rate of op-ups out of SIN is far higher than anywhere else (makes sense, given that you get to know the staff, develop a relationship etc).

We keep being told that EK are going to implement a formula for determining upgrades, (which is based on criteria such as fare basis, status, customer score, etc etc) but no further news as yet.

I'm afraid EK's op-up policy is anything but transparent and consistent as you would hope. Good luck. Let us know how you go...